Modelling and Experiments Concerning Dendrite Re-Melting and Its Role in Microstructural Evolution in Spray Formed Ni Superalloys
This paper presents a combined experimental and modelling approach to understand dendrite fragmentation of atomised metal alloy droplets during deposition in spray forming, and to study quantitatively the relationship between this dendrite fragmentation behavior and subsequent microstructural evolution. A Gleeble 3500 physical simulator was used to create controlled thermal shock conditions in solid-liquid mixtures of Ni superalloy IN718 atomised powders, which simulated the environment of droplet deposition during the twin-atomiser spray forming of large diameter IN718 alloy billets at BIAM. The experiments were complemented by phase field modelling studies at Oxford. Experiment and modelling supported the hypothesis that the characteristic equiaxed spray formed microstructure depends critically upon the rapid remelting and thermal shock of fine-scale dendrites in solid particles in the spray to provide a high density of embryonic grains.
Jian-Feng Nie and Allan Morton
Y. Zhang et al., "Modelling and Experiments Concerning Dendrite Re-Melting and Its Role in Microstructural Evolution in Spray Formed Ni Superalloys", Materials Science Forum, Vols. 654-656, pp. 1363-1366, 2010